Physalaemin-like immunoreactive material (PHLIM) is the designation of the relatively prominent rabbit stomach macromolecule(s) whose structure(s) is/are not yet known. PHLIM appears to be glycoprotein and is presumed to be the metabolic precursor of the physalaemin-like octapeptide, PHLIP- 8: less than Glu-Val-Asp-Pro-Asn-Ile-Gln-Ala. Prior immunohistochemical studies, using antiserum to the amphibian peptide physalaemin, had indicated widespread distribution of cross-reactivity in the rat; thus, we proposed repeating that type of investigation using an appropriate antiserum to PHLIP-8. An attempt to develop an antiserum to (Lys 0)-PHLIP-8 was undertaken; however, problems encountered in obtaining either a suitable isotope-labelled analog or antigen, or both, have delayed our reexamination of the immunohistochemical profile of the physalaemin-like peptides in the mammal. This project will be continued by coupling (Lys9)-PHLIP-8 to hemocyanin as the source of the antigen and the preparation of the new analog polyclonal antibodies. This approach will provide antibodies that recognize the N-terminal portion of PHLIP-8 (which has homology to physalaemin). This study directly impinges upon oat-cell carcinoma (which contains a physalaemin-related peptide), diseases involving glycoproteins, and PHLIM function throughout the mammalian digestive and respiratory tracts.